The present invention relates to a new and improved construction of gear measuring machine for inspecting or checking helical gears.
Generally speaking, the gear measuring machine for inspecting helical gears of the present development is of the type comprising a pick-up or feeler and a device for compensating the various feeler tip sizes or magnitudes and helix angles, and which device is connected to a radius transmitter or indicator and an angle transmitter or indicator.
A gear measuring machine of this type has become known to the art from the pamphlet A 59-D 3.77-2000u, published in March 1977 by MAAG Gear-Wheel Company Ltd. This machine, during profile measurements, enables compensating for the various feeler tip sizes and for the helix angles, but there only can be adjusted therewith a limited number of discrete feeler tip sizes by means of decade switches. For these feeler tip sizes the compensation for the helix angle then is performed by means of a potentiometer. Compensation by means of a potentiometer naturally is not very precise, so that the zero point, which has been corrected by virtue of the feeler radius and the helix angle, equally cannot be precisely determined. This zero or null point is required if charts or diagrams which have measured the generating or roll path at a gear checking or inspection machine are thereafter to be employed at a gear processing or fabricating machine. Furthermore, the compensations performed by means of the potentiometer are hardly reproducible even at the gear measuring machine, since it is practically impossible to adjust the potentiometer to the exact same value during a later measuring operation. Additionally, the heretofore known gear measuring machine only delivers measuring values in the perpendicular or normal section, i.e. values which have been measured by means of deflections of the feeler which are normal or perpendicular to the tooth flank. However, at gear processing machines the machining of gear flanks of gears often is performed from an end plane. Thus, there are required measuring values in the end section, which are not delivered by the prior art machine.